JP7202604B2 - III-nitride semiconductor device, manufacturing method thereof, semiconductor wafer manufacturing method, and template substrate manufacturing method - Google Patents

Description

The technical field of the present specification relates to a Group III nitride semiconductor device using plasma, a method for manufacturing the same, a method for manufacturing a semiconductor wafer, and a method for manufacturing a template substrate.

In group III nitride semiconductors represented by GaN, the bandgap changes from 0.6 eV to 6 eV by changing the composition. Therefore, group III nitride semiconductors are applied to light-emitting devices, laser diodes, light-receiving devices, etc. corresponding to a wide range of wavelengths from near-infrared to deep-ultraviolet.

In addition, group III nitride semiconductors have a high breakdown electric field strength and a high melting point. Therefore, III-nitride semiconductors are expected to replace GaAs-based semiconductors as materials for high-power, high-frequency, and high-temperature semiconductor devices. Along with this, HEMT elements and the like are being researched and developed.

As a method for epitaxially growing a Group III nitride semiconductor, for example, there is a metalorganic chemical vapor deposition method (MOCVD method). The MOCVD method uses a large amount of ammonia gas. Therefore, it is necessary to provide an abatement device for removing ammonia from the MOCVD furnace. Moreover, the running cost of ammonia is high. Then, a semiconductor layer is formed by a reaction between the organometallic gas and ammonia. In order to cause this reaction, it is necessary to raise the substrate temperature to a high temperature. If the substrate temperature is high, it is difficult to grow an InGaN layer with a high In concentration with high quality. Moreover, warping is likely to occur due to the difference in thermal expansion between the growth substrate and the semiconductor layer.

Therefore, the present inventors have developed a REMOCVD (Radial Enhanced Metal Organic Chemical Vapor Deposition) method in which an organic metal gas containing a group III metal is not turned into plasma, but a gas containing nitrogen atoms is turned into plasma and supplied to a growth substrate. (Patent Document 1). The technique of Patent Document 1 can grow GaN or the like at a low temperature. Therefore, the stress caused by the difference in thermal expansion coefficients can be suppressed.

JP 2015-99866 A JP 2016-20299 A

By the way, sapphire substrates and GaN substrates are expensive. Therefore, it is preferable to form a Group III nitride semiconductor film on an inexpensive Si(111) substrate. However, it is not necessarily easy to deposit a high-quality Group III nitride semiconductor film on a Si(111) substrate.

For example, there is a mismatch between the lattice constant of GaN and the lattice constant of a Si(111) substrate (see paragraph [0026] of Patent Document 2). In addition, it is said that when an AlN buffer layer is formed on a Si (111) substrate, defects such as discontinuous planes and dislocations occur in the GaN layer grown thereon (Patent Document 2, paragraph [0005] reference). Therefore, in Patent Document 2, a technique is developed in which NH ₃ preflow is performed to grow an AlN buffer layer (see FIGS. 2, 4, etc. of Patent Document 2).

However, the NH ₃ preflow may not sufficiently nitride the surface of the Si(111) substrate. Also, the poor crystallinity of the AlN buffer layer requires an initial nucleation layer 14 and a thick top layer 15 . Therefore, it is preferable to form an AlN layer that is thinner and more excellent in crystallinity.

The technology of the present specification has been made to solve the problems of the conventional technology described above. The problem is to develop a group III nitride semiconductor device capable of forming a film of a group III nitride semiconductor having excellent crystallinity on a Si substrate, a method for manufacturing the same, a method for manufacturing a semiconductor wafer, and a method for manufacturing a template substrate. to provide.

A method for manufacturing a group III nitride semiconductor device according to a first aspect includes a substrate nitrogen treatment step of nitrogen-treating the surface of a Si(111) substrate to form an N layer, and a first step of forming an Al layer on the N layer. 1 and a second step of forming an N layer on the Al layer. In this manufacturing method, the AlN layer is formed by repeating the first step and the second step. In the substrate nitrogen treatment step, the nitrogen radicals are supplied to the Si (111) substrate by passing the nitrogen gas through the plasma generation region and then blocking the ions, electrons, and light to allow the nitrogen radicals to pass therethrough. ) forming the N layer by chemically bonding N atoms to Si atoms on the substrate surface ; In the first step, the Al-containing gas is supplied to the Si(111) substrate without allowing the Al-containing gas containing Al atoms to pass through the plasma generating region. In the second step, the nitrogen radicals are supplied to the Si(111) substrate by passing the nitrogen gas through the plasma generating region and then blocking the ions, electrons and light and allowing the nitrogen radicals to pass through .

In this method of manufacturing a Group III nitride semiconductor device, a Si(111) substrate is nitrided using nitrogen radicals, and then an Al layer and an N layer are laminated at the atomic layer level. Therefore, Al atoms and N atoms are preferably coordinated. Therefore, an AlN layer with excellent crystallinity is formed.

In this specification, a group III nitride semiconductor device capable of forming a film of a group III nitride semiconductor having excellent crystallinity on a Si substrate, a method for manufacturing the same, a method for manufacturing a semiconductor wafer, and a method for manufacturing a template substrate are provided. provided.

It is a figure which shows the structure of the semiconductor wafer of 1st Embodiment. FIG. 2 is an enlarged schematic view of the boundary surface between the substrate Sa1 and the AlN layer F1 of the first embodiment; 4 is a schematic diagram showing the atomic arrangement near the interface between the substrate Sa1 and the AlN layer F1 of the first embodiment; FIG. FIG. 2 is an enlarged schematic view of a conventional interface between a substrate and an AlN layer; FIG. 2 is a schematic diagram showing the atomic arrangement near the interface between a conventional substrate and an AlN layer; It is a figure which shows schematic structure of the manufacturing apparatus in 1st Embodiment. 4 is a timing chart showing the relationship between the supply of the first gas and the output of the high-frequency potential applied to the showerhead electrode by the RF power supply. FIG. 10 is a diagram showing the structure of the MIS semiconductor device of the second embodiment; It is a figure which shows the structure of the light emitting element of 3rd Embodiment. It is a RHEED pattern when the temperature of the Si(111) substrate is 25°C. It is a RHEED pattern when the temperature of the Si(111) substrate is 300.degree. It is a RHEED pattern when the temperature of the Si(111) substrate is 600.degree. It is a RHEED pattern when the temperature of the Si(111) substrate is 900.degree.

Hereinafter, specific embodiments will be described with reference to the drawings, exemplifying a Group III nitride semiconductor device, a method for manufacturing the same, a method for manufacturing a semiconductor wafer, and a method for manufacturing a template substrate.

(First embodiment)
1. 1. Semiconductor Wafer FIG. 1 is a diagram showing the structure of a semiconductor wafer Wa1 of this embodiment. The semiconductor wafer Wa1 has a substrate Sa1, an AlN layer F1, and a semiconductor layer F2. The substrate Sa1 is a Si(111) substrate. The AlN layer F1 is a layer laminated at the atomic layer level. The semiconductor layer F2 is a single crystal semiconductor layer made of a Group III nitride semiconductor. The semiconductor layer F2 is, for example, a GaN layer. Thus, the semiconductor wafer Wa1 is obtained by epitaxially growing a group III nitride semiconductor on the main surface of the wafer.

Here, stacking at the atomic layer level means stacking layers of one atomic layer or more and three atomic layers or less. Therefore, the AlF layer F1 may be formed by stacking one atomic layer each of Al atoms and N atoms.

2. Boundary Surface Between Substrate and AlN Layer FIG. 2 is an enlarged schematic view of the boundary surface between the substrate Sa1 and the AlN layer F1 of the present embodiment. FIG. 3 is a schematic diagram showing the atomic arrangement near the interface between the substrate Sa1 and the AlN layer F1 of this embodiment. As shown in FIGS. 2 and 3, Si atoms on the surface of the substrate Sa1 are bonded to nitrogen atoms. Nitrogen atoms bonded to Si atoms are bonded to Al atoms. In other words, the semiconductor wafer Wa1 of this embodiment has a bond of Si—N—Al—. Alternatively, it may be a bond of Si-N-...-Al-....

The AlN layer F1 has 4 atomic layers or more and 30 atomic layers or less. Here, the layer on the surface side of the Si(111) substrate in the AlN layer F1 is a layer of N atoms. The layer opposite to the Si(111) substrate in the AlN layer F1 is a layer of Al atoms. Since the AlN layer F1 is sufficiently thin, the lattice constant of the AlN layer F1 is close to that of the Si(111) substrate. The difference between the lattice constant of Si(111) and the lattice constant of the AlN layer is 10% or less. Preferably, it is 8% or less. More preferably, it is 6.25% or less. Note that, for example, an AlN layer of two atomic layers is a state of having an Al layer of one atomic layer and an N layer of one atomic layer.

3. Comparison with Conventional Semiconductor Wafer FIG. 4 is an enlarged schematic view of the interface between a conventional substrate and an AlN layer. FIG. 5 is a schematic diagram showing the atomic arrangement near the interface between the conventional substrate and the AlN layer. As shown in FIGS. 4 and 5, Si atoms on the surface of the substrate Sa1 are bonded to Al atoms. Al atoms bonded to Si atoms are bonded to nitrogen atoms. That is, conventional semiconductor wafers have bonds of Si--Al--N--.

4. Effect of Semiconductor Wafer of Present Embodiment In the semiconductor wafer Wa1 of the present embodiment, the Si(111) substrate is suitably nitrided. As will be described later, the AlN layer F1 is laminated on the Si atoms of the substrate Sa1 at the atomic layer level. Also, since the AlN layer F1 is sufficiently thin, the lattice constant of the AlN layer F1 is considered to be close to the lattice constant of the Si(111) substrate. Therefore, the crystallinity of the semiconductor layer F2 laminated on the AlN layer F1 is very excellent.

It is not necessarily easy to nitride the surface of the Si(111) substrate as in this embodiment.

5. Group III Nitride Semiconductor Device Manufacturing Apparatus FIG. 6 is a schematic configuration diagram of a group III nitride semiconductor device manufacturing apparatus 1000 according to the present embodiment. A manufacturing apparatus 1000 is for epitaxially growing a Group III nitride semiconductor. A manufacturing apparatus 1000 is a plasma generation apparatus that generates a plasma generation region inside a chamber. The manufacturing apparatus 1000 supplies an organometallic gas (first gas) containing a group III metal to the growth substrate without passing through the plasma generation region, and supplies a gas (second gas) containing nitrogen atoms to the plasma generation region. After passing through, it is supplied to the growth substrate.

A manufacturing apparatus 1000 includes a furnace body 1001, a shower head electrode 1100, a susceptor 1200, a heater 1210, a first gas supply pipe 1300, a gas introduction chamber 1410, a second gas supply pipe 1420, a metal Mesh 1500, RF power supply 1600, matching box 1610, plasma power pulse control unit 1620, first gas supply unit 1710, second gas supply unit 1810, gas containers 1910, 1920, 1930, constant temperature It has tanks 1911 , 1921 , 1931 , mass flow controllers 1720 , 1820 , 1830 , 1840 and a pulse valve 1850 . The manufacturing apparatus 1000 also has an exhaust port (not shown).

Showerhead electrode 1100 is the first electrode to which a periodic potential is applied. The showerhead electrode 1100 is made of stainless steel, for example. Of course, other metals may be used. The showerhead electrode 1100 is a plate-shaped electrode. The showerhead electrode 1100 is provided with a plurality of through holes (not shown) penetrating from the front surface to the back surface. These through holes communicate with gas introduction chamber 1410 and second gas supply pipe 1420 . Therefore, the second gas supplied from the gas introduction chamber 1410 to the inside of the furnace body 1001 is preferably converted into plasma.

The RF power supply 1600 is a potential applying section that applies a high frequency potential to the showerhead electrode 1100 . The plasma power pulse controller 1620 is a device for applying high frequency pulses to the showerhead electrode 1100 .

The susceptor 1200 is a substrate support for supporting the substrate Sa1. The material of the susceptor 1200 is graphite, for example. Also, other conductors may be used. Here, the substrate Sa1 is a growth substrate for growing a group III nitride semiconductor.

A first gas supply pipe 1300 is for supplying a first gas to the susceptor 1200 . In practice, the first gas is supplied to the substrate Sa1 supported by the susceptor 1200. FIG. Here, the first gas is an organometallic gas containing a Group III metal. Moreover, other carrier gases may be included. The first gas supply pipe 1300 has a ring-shaped ring portion 1310 . The ring portion 1310 of the first gas supply pipe 1300 is provided with 12 through holes (not shown) inside the ring portion 1310 . Thus, the first gas supply pipe 1300 has at least one or more through-holes. These through holes are ejection ports from which the first gas is ejected. Therefore, the first gas is jetted toward the inner side of ring portion 1310 . Also, these through holes are located between the susceptor 1200 and the metal mesh 1500 . Therefore, the first gas supply pipe 1300 is positioned away from the plasma generation region.

A second gas supply pipe 1420 is for supplying a second gas to the susceptor 1200 . In practice, the second gas is supplied to the space between the showerhead electrode 1100 and the metal mesh 1500 to supply the substrate Sa1 supported by the susceptor 1200 with the second gas. Here, the second gas is gas containing nitrogen gas. The second gas may be a mixed gas of nitrogen gas and hydrogen gas.

The gas introduction chamber 1410 temporarily accommodates a mixed gas of nitrogen gas and hydrogen gas, and is for supplying this mixed gas to the through-holes of the showerhead electrode 1100 .

Metal mesh 1500 is a metal mesh member for capturing charged particles. Metal mesh 1500 is made of stainless steel, for example. Of course, other metals may be used. A metal mesh 1500 is positioned between the showerhead electrode 1100 and the susceptor 1200 . Therefore, the metal mesh 1500 can suppress charged particles generated in the plasma generation region from going toward the growth substrate Sa1 supported by the susceptor 1200, as will be described later. Also, the metal mesh 1500 is arranged at a position between the showerhead electrode 1100 and the ring portion 1310 of the first gas supply pipe 1300 . Therefore, charged particles can be prevented from colliding with organometallic molecules containing a group III metal ejected from the ring portion 1310 of the first gas supply pipe 1300 . Also, the metal mesh 1500 is formed by overlapping a large number of meshes while shifting them little by little. That is, the linear portions of the second mesh are arranged at the positions of the openings of the first mesh. Therefore, light traveling in a straight line cannot pass through the metal mesh 1500 . In other words, the metal mesh 1500 does not pass electrons, ions, and light, but allows neutral radicals to pass.

The furnace body 1001 accommodates therein at least the shower head electrode 1100, the susceptor 1200, the ring portion 1310 of the first gas supply pipe 1300, and the metal mesh 1500. As shown in FIG. The furnace body 1001 is made of stainless steel, for example. Furnace body 1001 may be a conductor other than the above.

The furnace main body 1001, the metal mesh 1500, and the first gas supply pipe 1300 are conductive members, and are all grounded. Therefore, when a potential is applied to showerhead electrode 1100 , a voltage is applied between showerhead electrode 1100 , furnace main body 1001 and metal mesh 1500 . Then, it is considered that discharge occurs between at least one of the furnace body 1001 and the metal mesh 1500 and the shower head electrode 1100 . A high-frequency and high-strength electric field is formed directly under the showerhead electrode 1100 . Therefore, the position directly below the showerhead electrode 1100 is the plasma generation region.

Here, the second gas is turned into plasma in this plasma generating region. A plasma product is generated in the plasma generation region. The plasma products in this case are, for example, nitrogen radicals, hydrogen radicals, hydrogen nitride compounds, electrons, and other ions. Here, the hydrogen nitride-based compound includes NH, NH ₂ , NH ₃ , their excited states, and others.

Also, the showerhead electrode 1100 and the susceptor 1200 are sufficiently separated. The distance between the showerhead electrode 1100 and the susceptor 1200 is 40 mm or more and 200 mm or less. More preferably, it is 40 mm or more and 150 mm or less. If the distance between the showerhead electrode 1100 and the susceptor 1200 is short, the plasma generation area may extend to the susceptor 1200 . If the distance between the showerhead electrode 1100 and the susceptor 1200 is 40 mm or more, there is almost no possibility that the plasma generation region will extend to the susceptor 1200 . Therefore, it is possible to suppress the charged particles from reaching the substrate Sa1. Also, if the distance between the showerhead electrode 1100 and the susceptor 1200 is large, it becomes difficult for nitrogen radicals, hydrogen nitride-based compounds, and the like to reach the substrate Sa1 held by the susceptor 1200 . These distances also depend on the size of the plasma generation region and other plasma conditions.

The showerhead electrode 1100 is arranged at a position farther from the through hole of the ring portion 1310 of the first gas supply pipe 1300 when viewed from the susceptor 1200 . The distance between the showerhead electrode 1100 and the through hole of the ring portion 1310 of the first gas supply pipe 1300 is 30 mm or more and 190 mm or less. More preferably, it is 30 mm or more and 140 mm or less. This is to prevent charged particles from mixing into the first gas, and to facilitate nitrogen radicals, hydrogen nitride compounds, and the like to reach the substrate Sa1. Therefore, the semiconductor layer is laminated on the substrate Sa1 by the plasmatized second gas and the plasmatized first gas. These distances also depend on the size of the plasma generation region and other plasma conditions.

The heater 1210 is for heating the substrate Sa1 supported by the susceptor 1200 via the susceptor 1200 .

Mass flow controllers 1720, 1820, 1830, 1840 are for controlling the flow rate of each gas. A pulse valve 1850 is for supplying an organometallic gas containing a group III metal in synchronism with pulses of a high frequency potential. Constant temperature baths 1911 , 1921 , 1931 are filled with antifreeze liquids 1912 , 1922 , 1932 . Gas containers 1910, 1920, and 1930 are containers for containing organometallic gases containing Group III metals. Gas containers 1910, 1920, and 1930 contain trimethylgallium, trimethylindium, and trimethylaluminum, respectively. Of course, an organometallic gas containing other Group III metals such as triethylgallium may also be used.

The manufacturing apparatus 1000 has an electron gun 1010 and a detector 1020 . The electron gun 1010 is for emitting electrons in a solid due to heat or an electric field. The detector 1020 is for detecting electrons scattered on the surface of the substrate Sa1. Electron gun 1010 and detector 1020 form part of the RHEED apparatus.

6. Manufacturing Conditions of Manufacturing Apparatus Table 1 shows manufacturing conditions of the manufacturing apparatus 1000 . The numerical ranges listed in Table 1 are only a guideline, and the numerical ranges are not necessarily required. The RF power is in the range of 100W to 1000W. The frequency of the periodic potential applied to showerhead electrode 1100 by RF power supply 1600 is in the range of 30 MHz to 300 MHz. The substrate temperature is in the range of 0° C. or higher and 900° C. or lower. The internal pressure of the manufacturing apparatus 1000 is within the range of 1 Pa or more and 10000 Pa or less.

[Table 1]
RF power 100W or more and 1000W or less Frequency 30MHz or more and 300MHz or less Substrate temperature 0°C or more and 900°C or less Internal pressure 1Pa or more and 10000Pa or less

7. Gas and Pulse Voltage FIG. 7 is a timing chart showing the relationship between the supply of the first gas and the second gas and the output of the high-frequency potential applied to the showerhead electrode 1100 by the RF power supply 1600 . The horizontal axis of FIG. 7 is time. The vertical axis in the upper diagram of FIG. 7 is the flow rate of trimethylaluminum (TMA). The vertical axis in the middle diagram of FIG. 7 is the flow rate of nitrogen gas. The vertical axis in the lower diagram of FIG. 7 is RF power.

As shown in FIG. 7, the supply of the first gas and the second gas and the supply of power by the RF power supply 1600 are repeated at regular intervals. As shown in FIG. 7, the manufacturing apparatus 1000 forms a film while alternately repeating a first period T1 and a second period T2.

7-1. Substrate Nitrogen Processing Process As shown in FIG. 7, in the substrate nitrogen processing process of period T0, nitrogen gas is supplied from the shower head electrode 1100 and the RF power supply 1600 is turned on. Therefore, the nitrogen gas is turned into plasma in the plasma generation region below the showerhead electrode 1100 . Nitrogen radicals, nitrogen ions, electrons, ultraviolet rays, and the like are generated in this plasma generation region.

On the other hand, TMA is not supplied to the substrate Sa1. Note that the showerhead electrode 1100 does not supply H ₂ gas.

Nitrogen ions and electrons generated in the plasma generation region are captured by the metal mesh 1500 . Light is blocked by metal mesh 1500 . Therefore, only nitrogen radicals reach the substrate Sa1. Then, the surface of the Si(111) substrate is nitrided. That is, nitrogen atoms are bonded to Si atoms.

At this time, one atomic layer or more and three atomic layers or less of nitrogen atoms are formed on the substrate Sa1. Since the surface state of the substrate Sa1 can be observed by the RHEED apparatus, the period T0 can be set in advance.

7-2. First Step As shown in FIG. 7, the first gas supply pipe 1300 supplies the first gas to the susceptor 1200 during the first period T1. Second gas supply pipe 1420 does not supply the second gas. In other words, nitrogen gas is not supplied to the interior of the furnace body 1001 . RF power supply 1600 is OFF. Therefore, the group III element is supplied to the substrate Sa1 of the susceptor 1200 during the first period T1. Therefore, in the first period T1, an Al layer of 1 atomic layer or more and 3 atomic layers or less is formed.

7-3. Second Step As shown in FIG. 7, the first gas supply pipe 1300 does not supply the first gas to the susceptor 1200 during the second period T2. During the second period T2, the second gas supply pipe 1420 supplies nitrogen gas. Note that the second gas supply pipe 1420 does not supply hydrogen gas. RF power supply 1600 also generates a plasma at output W1. Therefore, during the second period T2, nitrogen radicals are supplied to the substrate Sa1 of the susceptor 1200, but group III elements are not supplied to the substrate Sa1. Therefore, in the second period T2, an atomic layer level N layer is formed on the Al layer.

7-4. Time of First Period and Second Period The lengths of the first period T1 and the second period T2 may be determined based on the detection result by RHEED. By observing the pattern image obtained by RHEED, the required time for stacking at the atomic layer level can be obtained. Similarly, the time for the substrate nitrogen treatment step can also be obtained in the same manner.

7-5. Effect of First Period and Second Period In this way, nitrogen atoms are stacked on the Si of the Si(111) substrate at the atomic layer level, and Al atoms are stacked on these nitrogen atoms at the atomic layer level. Therefore, the Al plane of the AlN layer F1 is easily aligned. Also, the AlN layer F1 has good crystallinity. The film thickness of this AlN layer F1 is sufficiently thin. Therefore, it is considered that the lattice constant of the AlN layer F1 is close to the lattice constant of the Si(111) substrate.

8. Semiconductor Wafer Manufacturing Method In the semiconductor wafer manufacturing method of the present embodiment, a semiconductor layer is grown by a REMOCVD (Radial Enhanced Metal Organic Chemical Vapor Deposition) method. That is, the manufacturing apparatus 1000 of this embodiment is used to epitaxially grow a group III nitride semiconductor on the main surface of the substrate Sa1.

8-1. Cleaning of Substrate Here, a method for manufacturing a semiconductor wafer using the manufacturing apparatus 1000 of this embodiment will be described. First, a substrate Sa1 is prepared. The substrate Sa1 is placed on the susceptor 1200 inside the manufacturing apparatus 1000, and the substrate temperature is raised to about 900° C. while supplying hydrogen gas. This reduces the surface of the substrate Sa1 and cleans the surface of the substrate Sa1. The substrate temperature may be higher than this. Alternatively, hydrogen gas may be turned into plasma.

8-2. Substrate Nitrogen Processing Step Next, nitrogen gas is supplied from the shower head electrode 1100 into the furnace body 1001, and the RF power supply 1600 is turned on. At this time, the plasma power pulse controller 1620 is used to apply a pulse voltage to the shower head electrode 1100 .

In the substrate nitrogen treatment step, the nitrogen gas is supplied to the Si(111) substrate after passing through the plasma generating region.

Actually, nitrogen ions, nitrogen radicals, electrons, and ultraviolet rays are generated by passing the nitrogen gas through the plasma generation region. Metal mesh 1500 captures charged particles such as nitrogen ions and electrons. Moreover, the metal mesh 1500 is arranged by shifting a plurality of meshes. Therefore, the metal mesh 1500 does not transmit ultraviolet rays. Only neutral nitrogen radicals (including excited states) pass through the metal mesh 1500 and reach the substrate Sa1.

In the substrate nitrogen treatment step, the surface of the Si (111) substrate is nitrided at a temperature of 0° C. or higher and 100° C. or lower. As for the nitridation of the substrate Sa1, the nitridation period T0 may be set by observation using a RHEED apparatus.

Thus, the surface of the Si(111) substrate is nitrided. An N layer is formed on the surface of the Si(111) substrate.

8-3. AlN Layer Forming Step Next, an AlN layer F1 is formed on the surface-nitrided Si(111). In the AlN layer forming process, the first process and the second process are repeated. At this time, the plasma power pulse controller 1620 is used. In the first step, an Al layer is formed on the N layer. In the second step, an N layer is formed on the Al layer. A timing chart is shown in FIG. Note that the uppermost layer of the AlN layer F1 is preferably an Al layer. In this case, the first step of forming the Al layer is performed at the end of the AlN layer forming step.

8-3-1. First Step In the first step, the Al-containing gas containing Al atoms is supplied to the Si(111) substrate without allowing the Al-containing gas to pass through the plasma generating region. Therefore, plasma is not generated in the first step. Also, in the first step, an Al layer is formed at the atomic layer level. By using the RHEED device, the first period T1 can be set.

8-3-2. Second Step In the second step, the nitrogen gas is supplied to the Si(111) substrate after passing through the plasma generating region. In the second step, an N layer is formed at the atomic layer level. The second period T2 can be set by using the RHEED device.

8-4. Semiconductor Forming Step Next, a semiconductor layer F2 is formed on the AlN layer F1. At this time, the first gas and the second gas are simultaneously supplied into the furnace body 1001 . For example, the first gas is trimethylgallium and carrier gas, and the _second gas is _N2 gas and H2 gas. By simultaneously supplying the first gas and the second gas, in this case, a GaN layer is formed as the semiconductor layer F2 on the AlN layer F1.

8-5. Effects of the Manufacturing Method of the Present Embodiment In the semiconductor wafer manufacturing method of the present embodiment, the AlN layer F1 is grown at the atomic layer level. Therefore, Al atoms and N atoms hardly react in a space inside the furnace body 1001 away from the substrate Sa1. Therefore, the AlN layer F1 having excellent crystallinity can be formed.

9. Modification 9-1. Template Substrate Instead of the semiconductor wafer Wa1 of this embodiment, a template substrate may be manufactured. The template substrate is obtained by removing the semiconductor layer F2 from the semiconductor wafer Wa1.

9-2. Period for Generating Plasma in Plasma Generation Region As shown in FIG. 7, when supplying Al-containing gas containing Al atoms, no plasma is generated in the plasma generation region. However, the manufacturing apparatus 1000 has a configuration that does not allow the Al-containing gas to pass through the plasma generation region. Therefore, plasma may be generated when supplying the Al-containing gas.

9-3. Period of Flowing Nitrogen Gas In FIG. 7, nitrogen gas is not flowed during the first period T1 during which TMA is flowed. However, nitrogen gas may be flowed during the first period T1. Since the RF power is 0 during the first period T1, the nitrogen gas is not turned into plasma even if it is supplied during the first period T1.

9-4. Semiconductor Layer Forming Step In the semiconductor layer forming step, film formation may be performed at the atomic layer level. In this case, the crystallinity of the semiconductor layer F2 is improved, but the film formation time is lengthened.

9-5. Combination The above modifications may be freely combined.

(Second embodiment)
A second embodiment will be described. The semiconductor device of this embodiment is a MIS semiconductor element having a Group III nitride semiconductor layer.

1. MIS Type Semiconductor Device FIG. 8 is a schematic configuration diagram showing the structure of the MIS type semiconductor device 100 of this embodiment. As shown in FIG. 8, the MIS semiconductor device 100 includes a substrate 110, a buffer layer 120, a GaN layer 130, an AlGaN layer 140, an insulating film 150, a source electrode S1, a gate electrode G1, a drain electrode and a and D1. A source electrode S<b>1 and a drain electrode D<b>1 are formed on the AlGaN layer 140 . There is an insulating film 150 between the gate electrode G1 and the groove 141 of the AlGaN layer 140 . Here, the buffer layer 120 is preferably an AlN layer.

2. Method for Manufacturing MIS Type Semiconductor Device In the method for manufacturing the MIS type semiconductor device 100 of this embodiment, a semiconductor layer is grown by a REMOCVD (Radial Enhanced Metal Organic Chemical Vapor Deposition) method. That is, a semiconductor layer is grown using the manufacturing apparatus 1000 of the first embodiment.

2-1. Semiconductor Layer Forming Step A III-nitride semiconductor layer is formed on the substrate 110 using the manufacturing apparatus 1000 of the first embodiment. The conditions used here are substantially the same as those in the semiconductor wafer manufacturing method described in the first embodiment. A buffer layer 120 , a GaN layer 130 and an AlGaN layer 140 are formed on the substrate 110 . In order to form each of the above semiconductor layers, the raw material gas may be switched as appropriate.

2-2. Step of Forming Recesses Next, grooves 141 are formed in the AlGaN layer 140 by etching such as ICP.

2-3. Insulating Film Forming Step Next, an insulating film 150 is formed in the trench 141 .

2-4. Electrode Forming Step Next, a source electrode S 1 and a drain electrode D 1 are formed on the AlGaN layer 140 . Also, the gate electrode G1 is formed at the location of the trench 141 with the insulating film 150 interposed therebetween. Note that the source electrode S1 and the drain electrode D1 may be formed before the insulating film 150 is formed. As described above, the MIS type semiconductor device 100 is manufactured.

(Third Embodiment)
A third embodiment will be described. The semiconductor device of this embodiment is a semiconductor light-emitting element having a Group III nitride semiconductor layer.

1. Semiconductor Light Emitting Device FIG. 9 is a schematic configuration diagram showing the structure of the light emitting device 200 of this embodiment. As shown in FIG. 9, the light emitting device 200 has a Group III nitride semiconductor layer. The light-emitting device 200 includes a substrate 210, a buffer layer 220, an n-GaN layer 230, a light-emitting layer 240, a p-AlGaN layer 250, a p-GaN layer 260, a p-electrode P1, an n-electrode N1, have The light emitting layer 240 has well layers and barrier layers. The well layer has, for example, an InGaN layer. The barrier layer has, for example, an AlGaN layer. These laminated structures are examples, and laminated structures other than those described above may be used. Here, the buffer layer 220 is preferably an AlN layer.

2. Method for Manufacturing Semiconductor Light Emitting Device In the method for manufacturing the light emitting device 200 of the present embodiment, a semiconductor layer is grown by a REMOCVD (Radial Enhanced Metal Organic Chemical Vapor Deposition) method. That is, a semiconductor layer is grown using the manufacturing apparatus 1000 of the first embodiment.

2-1. Semiconductor Layer Forming Step A III-nitride semiconductor layer is formed on the substrate 210 using the manufacturing apparatus 1000 of the first embodiment. The conditions used here are substantially the same as those in the semiconductor wafer manufacturing method described in the first embodiment. A buffer layer 220 , an n-GaN layer 230 , a light emitting layer 240 , a p-AlGaN layer 250 and a p-GaN layer 260 are formed on the substrate 210 . In order to form each of the above semiconductor layers, the raw material gas may be switched as appropriate.

2-2. Step of Forming Recess Next, a recess is formed from the p-GaN layer 260 to the middle of the n-GaN layer 230 by etching such as ICP. As a result, the exposed portion of the n-GaN layer 230 is exposed.

2-3. Electrode Forming Step Next, an n-electrode N 1 is formed on the exposed portion of the n-GaN layer 230 . Also, a p-electrode P1 is formed on the p-GaN layer 260. As shown in FIG.

2-4. Other Steps Other steps such as an annealing step and a step of forming an insulating film may be performed.

(experiment)
1. RHEED
In this experiment, the experiment was conducted using the manufacturing apparatus 1000 shown in FIG. The internal pressure of the manufacturing apparatus 1000 was 300Pa. A Si (111) substrate of 8 mm square and 400 μm thick was used as a growth substrate.

The temperature of the Si(111) substrate was raised to 300° C. while flowing H ₂ gas at 1000 sccm (cleaning step). Next, the RF power was set to 100 W, and N ₂ gas was flowed at 750 sccm (substrate nitrogen treatment step). The RHEED pattern was observed while changing the temperature of the Si(111) substrate at this time.

FIG. 10 is a RHEED pattern when the temperature of the Si(111) substrate is 25.degree. FIG. 11 is a RHEED pattern when the temperature of the Si(111) substrate is 300.degree. FIG. 12 shows the RHEED pattern when the temperature of the Si(111) substrate is 600.degree. FIG. 13 shows the RHEED pattern when the temperature of the Si(111) substrate is 900.degree.

As shown in FIGS. 10 to 13, streak lines were observed when the temperature of the Si(111) substrate was 25.degree. C. and 300.degree. However, when the temperature of the Si(111) substrate was 600° C. and 900° C., no streak line was observed. Therefore, the temperature of the Si(111) substrate should be 0° C. or higher and 300° C. or lower.

2. Surface Roughness In this experiment, the manufacturing apparatus 1000 shown in FIG. 6 was used. The internal pressure of the manufacturing apparatus 1000 was 100-150Pa. A Si (111) substrate of 8 mm square and 400 μm thick was used as a growth substrate.

The temperature of the Si(111) substrate was raised to 300° C. while maintaining the internal pressure of the furnace at 150 Pa and flowing H ₂ gas at 1000 sccm (cleaning step). Next, the substrate temperature was returned to room temperature, the RF power was set to 100 W, and N ₂ gas was supplied at 750 sccm (substrate nitrogen treatment step). Then, the temperature of the Si(111) substrate was raised to 600.degree.

An Al film was formed by flowing TMA (trimethylaluminum) for 20 seconds while flowing N ₂ gas at 750 sccm. After that, the introduction of TMA was stopped, the RF power was changed to 100 W, and the N ₂ gas was plasmatized to nitride the Al. The introduction of TMA and the termination of TMA were repeated 20 times (AlN layer forming step).

When the substrate temperature was 25° C., the surface roughness (RMS) of the Si substrate after nitrogen treatment was 0.190 nm. When the substrate temperature was 300° C., the surface roughness (RMS) of the Si substrate after nitrogen treatment was 0.136 nm. When the substrate temperature was 600° C., the surface roughness (RMS) of the Si substrate after nitrogen treatment was 0.230 nm. When the substrate temperature was 900° C., the surface roughness (RMS) of the Si substrate after nitrogen treatment was 0.191 nm.

[Table 2]
Substrate temperature Surface roughness (RMS)
25°C 0.190 nm
300°C 0.136 nm
600°C 0.230 nm
900°C 0.191 nm

3. Lattice Constant This experiment was conducted using the manufacturing apparatus 1000 shown in FIG. The internal pressure of the manufacturing apparatus 1000 was 100-150Pa. A Si (111) substrate of 8 mm square and 400 μm thick was used as a growth substrate.

The temperature of the Si(111) substrate was raised to 300° C. while maintaining the internal pressure of the furnace at 150 Pa and flowing H ₂ gas at 1000 sccm (cleaning step). Next, the substrate temperature was returned to room temperature, the RF power was set to 100 W, and N ₂ gas was supplied at 750 sccm (substrate nitrogen treatment step). Then, the temperature of the Si(111) substrate was raised to 600.degree.

An Al film was formed by flowing TMA (trimethylaluminum) for 20 seconds while flowing N ₂ gas at 750 sccm. After that, the introduction of TMA was stopped, the RF power was changed to 100 W, and the N ₂ gas was plasmatized to nitride the Al. The introduction of TMA and the termination of TMA were repeated 10 times (AlN layer forming step).

Table 3 shows the measurement results. Table 4 shows the lattice constants (a-axis) of Si and AlN.

[Table 3]
Si streak line distance 0.8 cm
Approximate width of streak line 0.1 cm
AlN streak line distance 0.8 cm
Approximate width of streak line 0.1 cm

[Table 4]
Lattice constant of Si 5.431 Å
AlN lattice constant (a-axis) 3.112 Å

As shown in Table 3, within the approximate width of the Si and AlN streaklines, the Si and AlN streakline distances are equal. That is, the lattice constant of the deposited AlN is approximately equal to the lattice constant of Si. Considering the approximate width of the streak line, the difference between the lattice constant of the deposited AlN and the lattice constant of Si is 6.25% or less. At least, it can be said that the difference between the lattice constant of AlN and the lattice constant of Si is within 10%.

As shown in Table 4, the difference between the lattice constant of ordinary Si(111) and that of AlN is about 18.9%.

(Appendix)
A method for manufacturing a Group III nitride semiconductor device according to a first aspect includes a substrate nitrogen treatment step of nitrogen-treating the surface of a Si(111) substrate to form an N layer, and a second step of forming an Al layer on the N layer. 1 and a second step of forming an N layer on the Al layer. In this manufacturing method, the first step and the second step are repeated. In the substrate nitrogen treatment step, the nitrogen gas is supplied to the Si(111) substrate after passing through the plasma generating region. In the first step, the Al-containing gas is supplied to the Si(111) substrate without allowing the Al-containing gas containing Al atoms to pass through the plasma generating region. In the second step, the nitrogen gas is supplied to the Si(111) substrate after passing through the plasma generating region.

In the method for manufacturing a Group III nitride semiconductor device according to the second aspect, plasma is not generated in the first step.

In the method of manufacturing a group III nitride semiconductor device according to the third aspect, in the substrate nitrogen treatment step, the surface of the Si(111) substrate is nitrided at a temperature of 0° C. or higher and 100° C. or lower.

In the method of manufacturing a Group III nitride semiconductor device according to the fourth aspect, in the first step, an Al layer at the atomic layer level is formed. In the second step, an atomic layer level N layer is formed.

A semiconductor wafer manufacturing method according to a fifth aspect comprises a substrate nitrogen treatment step of nitrogen-treating the surface of a Si(111) substrate to form an N layer, and a first step of forming an Al layer on the N layer. and a second step of forming an N layer on the Al layer. In this manufacturing method, the first step and the second step are repeated. In the substrate nitrogen treatment step, the nitrogen gas is supplied to the Si(111) substrate after passing through the plasma generating region. In the first step, the Al-containing gas is supplied to the Si(111) substrate without allowing the Al-containing gas containing Al atoms to pass through the plasma generating region. In the second step, the nitrogen gas is supplied to the Si(111) substrate after passing through the plasma generating region.

A method for manufacturing a template substrate according to a sixth aspect comprises a substrate nitrogen treatment step of nitrogen-treating the surface of a Si(111) substrate to form an N layer, and a first step of forming an Al layer on the N layer. and a second step of forming an N layer on the Al layer. In this manufacturing method, the first step and the second step are repeated. In the substrate nitrogen treatment step, the nitrogen gas is supplied to the Si(111) substrate after passing through the plasma generating region. In the first step, the Al-containing gas is supplied to the Si(111) substrate without allowing the Al-containing gas containing Al atoms to pass through the plasma generating region. In the second step, the nitrogen gas is supplied to the Si(111) substrate after passing through the plasma generating region.

A group III nitride semiconductor device in a seventh aspect has a Si(111) substrate and an AlN layer on the Si(111) substrate. The AlN layer is 30 atomic layers or less. The difference between the lattice constant of Si(111) and the lattice constant of the AlN layer is 10% or less.

DESCRIPTION OF SYMBOLS 1000... Manufacturing apparatus 1001... Furnace main body 1010... Electron gun 1020... Detecting part 1100... Shower head electrode 1200... Susceptor 1210... Heater 1300... First gas supply pipe 1410... Gas introduction chamber 1420... Second gas supply pipe 1500 ... Metal mesh 1600 ... RF power supply 1610 ... Matching box 1620 ... Plasma power pulse controller 1850 ... Pulse valve

Claims (7)

a substrate nitrogen treatment step of nitrogen-treating the surface of the Si(111) substrate to form an N layer;
a first step of forming an Al layer on the N layer;
a second step of forming an N layer on the Al layer;
has
forming an AlN layer by repeating the first step and the second step;
In the substrate nitrogen treatment step,
After passing nitrogen gas through a plasma generation region, ions, electrons, and light are blocked and nitrogen radicals are allowed to pass through, thereby supplying the nitrogen radicals to the Si(111) substrate and reducing the surface of the Si(111) substrate. forming the N layer by chemically bonding N atoms to the Si atoms of
In the first step,
supplying the Al-containing gas to the Si (111) substrate without allowing the Al-containing gas containing Al atoms to pass through the plasma generation region;
In the second step,
Group III characterized in that the nitrogen radicals are supplied to the Si(111) substrate by passing the nitrogen gas through the plasma generation region and then blocking ions, electrons, and light to allow the nitrogen radicals to pass through. A method for manufacturing a nitride semiconductor device. In the method for manufacturing a group III nitride semiconductor device according to claim 1,
In the first step,
A method for manufacturing a group III nitride semiconductor device, characterized in that plasma is not generated. In the method for manufacturing a group III nitride semiconductor device according to claim 1 or 2,
In the substrate nitrogen treatment step,
A method for manufacturing a Group III nitride semiconductor device, wherein the surface of the Si(111) substrate is nitrided at a temperature of 0°C or higher and 100°C or lower. In the method for manufacturing a group III nitride semiconductor device according to any one of claims 1 to 3,
In the first step,
forming the Al layer at the atomic layer level;
In the second step,
A method for manufacturing a Group III nitride semiconductor device, wherein the N layer is formed at an atomic layer level. a substrate nitrogen treatment step of nitrogen-treating the surface of the Si(111) substrate to form an N layer;
a first step of forming an Al layer on the N layer;
a second step of forming an N layer on the Al layer;
has
forming an AlN layer by repeating the first step and the second step;
In the substrate nitrogen treatment step,
After passing nitrogen gas through a plasma generation region, ions, electrons, and light are blocked and nitrogen radicals are allowed to pass through, thereby supplying the nitrogen radicals to the Si(111) substrate and reducing the surface of the Si(111) substrate. forming the N layer by chemically bonding N atoms to the Si atoms of
In the first step,
supplying the Al-containing gas to the Si (111) substrate without allowing the Al-containing gas containing Al atoms to pass through the plasma generation region;
In the second step,
A semiconductor wafer, wherein said nitrogen radicals are supplied to said Si(111) substrate by passing nitrogen gas through said plasma generating region and then blocking ions, electrons and light and allowing said nitrogen radicals to pass through said plasma generation region. manufacturing method. a substrate nitrogen treatment step of nitrogen-treating the surface of the Si(111) substrate to form an N layer;
a first step of forming an Al layer on the N layer;
a second step of forming an N layer on the Al layer;
has
forming an AlN layer by repeating the first step and the second step;
In the substrate nitrogen treatment step,
After passing nitrogen gas through a plasma generation region, ions, electrons, and light are blocked and nitrogen radicals are allowed to pass through, thereby supplying the nitrogen radicals to the Si(111) substrate and reducing the surface of the Si(111) substrate. forming the N layer by chemically bonding N atoms to the Si atoms of
In the first step,
supplying the Al-containing gas to the Si (111) substrate without allowing the Al-containing gas containing Al atoms to pass through the plasma generation region;
In the second step,
A template substrate, wherein the nitrogen radicals are supplied to the Si(111) substrate by passing the nitrogen gas through the plasma generating region and then blocking ions, electrons, and light and allowing the nitrogen radicals to pass through. manufacturing method. a Si(111) substrate;
an AlN layer on the Si(111) substrate;
In the group III nitride semiconductor device having
Si atoms and N atoms are chemically bonded at the interface between the Si(111) substrate and the AlN layer,
The AlN layer is
30 atomic layers or less,
The difference between the lattice constant of the Si(111) and the lattice constant of the AlN layer is
A III-nitride semiconductor device, wherein the content is 10% or less.

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